diff --git a/README.md b/README.md
index 5cf0efe..9fbde28 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,6 @@ Custom firmware USB device: 1CCF:2333
 
 ```
 $ git clone ...
-$ zig build
+$ zig build -Drelease-fast=true
 $ ls zig-out/lib/chuniio_tasoller.dll
 ```
diff --git a/build.zig b/build.zig
index 0f0ed0b..fa3585f 100644
--- a/build.zig
+++ b/build.zig
@@ -3,10 +3,13 @@ const CrossTarget = std.zig.CrossTarget;
 
 pub fn build(b: *std.build.Builder) void {
     const target = CrossTarget{ .os_tag = .windows, .cpu_arch = .i386, .abi = .msvc };
+    
     const lib = b.addSharedLibrary("chuniio_tasoller", "src/main.zig", .unversioned);
+    lib.setBuildMode(b.standardReleaseOptions());
     lib.setTarget(target);
     lib.install();
-    const exe = b.addExecutable("tasoller_test", "src/main.zig");
-    exe.setTarget(target);
-    exe.install();
+    
+    // const exe = b.addExecutable("tasoller_test", "src/main.zig");
+    // exe.setTarget(target);
+    // exe.install();
 }